Various detection schemes are used on a daily basis to detect the presence or passing of vehicles for aiding in the control of traffic signal systems, traffic monitoring systems, gated access systems, and many other related applications. For instance, when used in association with monitoring traffic, vehicle detection systems detect the presence and/or passing of vehicles on roadways and/or intersections thereof to determine traffic conditions, detect common congestion areas, and the like. For gated access applications, vehicle detection systems use the detected presence of a vehicle to automatically deny or allow access therethrough. While currently existing schemes may adequately detect vehicles with some accuracy, there is still room for improvement.
One commonly used approach to vehicle detection employs induction loops or coils that are installed beneath the surface of the pavement or roadway and designed to detect the presence or the passing of vehicles thereover. More particularly, an electric current is supplied through the induction coil at fixed frequencies to generate a predefined inductance. Due to the mostly metallic body of vehicles, when a vehicle is positioned over an induction loop, it induces eddy currents which further vary the inductance in the coils. By monitoring or detecting these deviations in inductance, the vehicle detection system is able to determine whether a vehicle has passed over an induction loop or is standing over the induction loop, and the like.
However, induction loop systems are extremely costly to implement and maintain. Specifically, the installation of induction loop systems entails a great amount of labor just to cut the appropriate grooves within the pavement for the induction coils. The process further involves inserting the inductions coils within the grooves as well as patching the grooves with material sufficient to withstand changing weather conditions and protect the coils from other forms of contamination. While the installation process alone is labor-intensive and costly, such drawbacks are further compounded by the need to shutdown one or more lanes of traffic per installation of an induction loop system and for the full duration thereof.
Other more recent developments employ magnetic sensor-based schemes to detect passing or standing vehicles. These systems generally rely on a magnetometer or related magnetic sensors which detect the direction and magnitude of surrounding magnetic fields, or the Earth's magnetic fields, along one or more axes. Typically, a magnetometer probe is placed above ground but proximate to the anticipated travel path of a vehicle, beneath the surface of the pavement, or in any other position suitable for detecting changes in the Earth's magnetic fields or interference caused by vehicles passing or standing thereby. However, many magnetic sensor-based systems generally employ wireless means of communication, such as radio-frequency, or the like, between the probe and the control box associated therewith, which introduces a vast array of undesirable interference. More particularly, changing weather conditions, surrounding structures, and many other environmental factors can adversely affect the wireless transmission of probe data, and thus, the overall consistency and reliability of the vehicle detection system.
Accordingly, there is a need for a cost-efficient, simplified, and yet reliable means of detecting vehicle proximity as well as communicating such detection data between a probe and a control system associated therewith. Moreover, there is a need for vehicle detection systems and methods which reduce susceptibility to interference from environmental surroundings, while also reducing the overall costs associated with implementation, control and maintenance thereof. The present disclosure is directed at addressing one or more of the deficiencies set forth above.